This can be done with a datatable in between. You fill the datatable with the recordset and set that to the datasource. Then you can use the SelectedValue from the C1Combo in the recordset.Find method to find the recordset bookmark.
rs.Find(
"ProductID = '" & C1Combo1.SelectedValue & "'")
[rs.Bookmark is set]
This code would be placed in the SelectedValueChanged event, and C1Combo.ValueMember = "ProductID"
Hope that helps,
Greg L